Biosensors generally comprise devices integrated with a biological sensing element (often a product derived from a living system) and a signal transducer, which can provide a recognition signal of the presence of a specific substance. The biological sensing element (which can include, for example, an enzyme, an antibody, a nucleic acid, and/or another analyte-detecting molecule) generally determines the specificity of the biosensor. The specific binding or reaction between the target and the receptor (or the biological sensing element) can introduce a signal that is then transduced and measured. Biosensors can be configured for macromolecular recognition, such as with human cells of different types, viruses, and pathogenic organisms. Therefore, there is a far-reaching diagnostic utility in these devices ranging from applications towards human health, food safety, drug response, and personalized medicine.
Biosensors may be categorized by their operational mechanism. Although optical biosensors using colorimetric, fluorescence, luminescence, and absorbance are industry and diagnostics standards, these strategies often necessitate target labeling and amplification. Also, the instrumentation footprint necessary to sensitively read optically-based signals is large compared with that achievable with devices incorporating nanotechnologies and microelectronics. Thus, technologies that improve the sensitivity, cost, instrumentation, and/or field applicability of biosensors are desirable.